diff --git a/morph/grid/local/README.rst b/morph/grid/local/README.rst
index 73bfbbdd2a11922fe696161fe8346d7e10157313..59f032a0fad5bf2fd328955db7649b3cd8b288e4 100644
--- a/morph/grid/local/README.rst
+++ b/morph/grid/local/README.rst
@@ -5,10 +5,18 @@ Set up and use a network of local development VMs
 (The author of this documentation wasted a lot of time trying to get Vagrant to work with KVM/libvirt.
 Issues with networking that looked like guest misconfigurations vanished after changing to the better-tested combination of Vagrant and VirtualBox.)
 
+This requires `NixOS <https://nixos.org/>`_.
+Nix without the OS will not work.
 
 Use the local development environment
 `````````````````````````````````````
 
+0. Add VirtualBox to your NixOs system configuration at ``/etc/nixos/configuration.nix``::
+
+    virtualisation.virtualbox.host.enable = true;
+    # Use VirtualBox installation without GUI and Qt dependency:
+    virtualisation.virtualbox.host.headless = true;
+
 1. Enter the morph local grid directory::
 
     cd morph/grid/local